Many attempts have been made in the past to mask or eliminate noxious odors and tastes of drugs to enhance the dosage compliance of patients who are required to take these drugs. Coatings which have been used in the case of solid water insoluble particulates have all suffered from deficiencies of one sort or another relating either to processing difficulties and working with the coating materials themselves or from limited success in performing the masking function.
One method of dealing with drugs of this sort is to coat them in the form of microparticles. The coating of particles by coacervation is well known. U.S. Pat. No. 3,594,327 issued to Julius G. Beesey discloses a process for making minute capsules in which minute particles of water and misible material and hydrophillic film forming polymeric material such as gelatin are dispersed in water and coacervated so that the polymeric material deposits around each of the minute particles. The polymeric material is then rendered rigid and water insoluble by a suitable fixative such as copper sulfate. The concept of coacervation of gelatin around particulate matter is also described in U.S. Pat. No. 3,317,434 issued to Vels et al. and U.S. Pat. No. 3,176,001 also issued to Vels. This gelatin which is of the porcine bovine type, is also used to form gelatin capsules and for some granulations.
While coacervation of conventional bovine and porcine gelatin is known, commercial processes utilizing coacervation of bovine and porcine gelatin as a coating for water insoluble drug particles is essentially nonexistent. The reason for this is that the gelatin must be heated to approximately 40.degree. C. before it is dissolved and ready for use. This temperature may adversely effect heat labile drugs and the increased temperature also makes the process difficult to work with.
Teleostean (fish) gelatin however is soluble in water at room temperature. This gelatin described for example in "Production of Glue and Gelatin from Fish" by J. C. Kernot and N. E. Speer, Department of Sol Ind. Research 2nd report of Adhesives Research Committee 1926, 23-33. Fish gelatin is also mentioned in U.S. Pat. No. 2,560,011 which teaches an extraction process for it. U.S. Pat. No. 3,873,749 issued to Carpenter et al. teaches a process for manufacturing a fish gelatin-alginate composition.